# GPT-6 Luna API

> OpenAI's GPT-6 Luna — the lightest GPT-6: fast, low-cost answers for high-volume work, served through one API.

- **Provider**: OpenAI
- **Model id**: `gpt-6-luna`
- **Modality**: text
- **Price**: 2.7–13.5 credits

## Overview

GPT-6 Luna is called in ONE step: POST your request and the answer comes back in the same response, in `text`. There is no task to poll.

## Authentication

All requests require a Bearer Token in the request header:

```
Authorization: Bearer YOUR_API_KEY
```

## Create Task

`POST https://you.bot/api/v1/generate`

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| modelId | string | Yes | Model id: `gpt-6-luna` |
| input | object | Yes | Input parameters object (see below) |
| callbackUrl | string | No | https URL we POST the finished task to. Signed with `X-Webhook-Signature` once you create a webhook signing key in Dashboard → Settings |

### input object parameters

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| prompt | string | Yes | Text value (example: Summarise in three bullet points why a lighthouse beam seems to sweep faster far out at sea.) |
| reasoning_effort | string | No | Control reasoning depth: Low for faster responses, High for deeper analysis (options: Low \| Medium \| High \| XHigh) (example: Medium) |
| stream | boolean | No | Send true to receive the reply as an event stream (Content-Type: text/event-stream). Omit it and you get a single JSON response — streaming is opt-in on this endpoint. (true/false) (example: true) |
| max_tokens | number | No | Maximum response length in tokens, reasoning included. Leave empty for the default of 4,096. (range 1-128000) |
| system | string | No | System instruction for the model. Defaults to "You are GPT-6 Luna, developed by OpenAI." when omitted. |
| messages | array | No | A conversation instead of a single `prompt`: an array of { "role", "content" } objects, where role is user, assistant, system or tool (a function result, with `tool_call_id`); an assistant message may carry `tool_calls` instead of text — see `tools`. Send the whole conversation — we do not limit how many messages it has, and we do not drop old ones; the model's context window is the limit. Send `prompt` or `messages`, not both. Do not flatten a conversation into one prompt with "User:" / "Assistant:" labels — the model reads that as a single message, and a model using web search then searches for the whole block instead of your question. |
| tools | array | No | Functions the model may call, up to 64. Each is { "type": "function", "function": { "name", "description", "parameters" } } with `parameters` a JSON Schema object (the flat Responses form and Anthropic's { "name", "description", "input_schema" } are accepted too); `strict: true` is accepted. When the model calls one, the response carries `toolCalls`: run the function, then send the conversation back in `messages` with the assistant's `tool_calls` and one { "role": "tool", "tool_call_id", "content" } message per result — and the same `tools` again. Function calling cannot be combined with web search in the same request. |
| tool_choice | string \| object | No | `auto` (the model decides; the default when `tools` is set), `none` (no call), `required` (at least one call), or { "type": "function", "function": { "name" } } to require that function. |

### Request example

```json
{
  "modelId": "gpt-6-luna",
  "input": {
    "prompt": "Summarise in three bullet points why a lighthouse beam seems to sweep faster far out at sea.",
    "reasoning_effort": "Medium",
    "stream": false,
    "max_tokens": 4096
  }
}
```

### Response example

```json
{
  "model": "gpt-6-luna",
  "text": "…",
  "creditsCharged": 0.01,
  "usage": {
    "inputTokens": 1400,
    "outputTokens": 120,
    "cachedInputTokens": 0,
    "cacheWriteTokens": 0
  }
}
```

## Query Task

`GET https://you.bot/api/v1/task/{taskId}?model=gpt-6-luna`

When `state` is `success`, the output is in `resultUrls`: `{ "text": "…" }`. (Text models return inline in the create response.)

## Error Codes

| Code | Description |
|------|-------------|
| 200 | Request successful |
| 400 | Invalid request parameters |
| 401 | Authentication failed — check API Key |
| 402 | Insufficient account balance |
| 403 | IP not allowed for this key, or the key is restricted to other models |
| 404 | Task not found, or it has expired |
| 409 | Duplicate request — an identical submit arrived moments ago. Nothing was charged; retry is safe |
| 413 | Payload too large — see the character and file-size limits for this model |
| 429 | Rate limit exceeded — retry after the Retry-After header |
| 500 | Internal server error |
| 504 | Upstream timed out — nothing was delivered; retry is safe |
| 400 · capability_not_supported | A capability was requested (e.g. `web_search: true`) that this model does not offer — refused, nothing charged |
| 400 · unknown_image_field | Images were sent under a key this model has no parameter for (input_urls, image_urls, imageUrl …) — refused rather than answered without them |
| 400 · image_input_not_supported | This model accepts text only — a request with an image is refused, not answered without it |
| 400 · tools_invalid | `tools` is malformed (not an array, a non-function tool, a bad or repeated name, parameters that are not an object schema), or a conversation with function calls was sent without `tools` — refused, nothing charged |
| 400 · tool_choice_invalid | `tool_choice` is malformed, names a function that is not in `tools`, or forces a call while `tools` is empty — refused, nothing charged |
| 400 · message_tool_call_invalid | An assistant `tool_calls` entry or a `tool` message is malformed, or a call and its result do not pair up (every call needs its own tool message right after it) — refused, nothing charged |
| 400 · message_tool_block_unsupported | A `tool_use` or `tool_result` content block was sent; send calls as `tool_calls` and results as `tool` messages instead |